Temperature dependent evolution of the electronic and local atomic structure in the cubic colossal magnetoresistive manganite La1-xSrxMnO3

Temperature dependent evolution of the electronic and local atomic structure in the cubic colossal magnetoresistive manganite La 1-x Sr x MnO 3 N. Mannella 1,2,a,b , C. H. Booth 3 , A. Rosenhahn 2,c , B. C. Sell 1,2 , A. Nambu 2,4,d , S. Marchesini 2,b ,B. S. Mun 1,2,b , S.-H. Yang 2,e , M. Watanabe 2,5 , K. Ibrahim 2,6 , E. Arenholz 7 , A. Young 7 , J. Guo 7 , Y. Tomioka 8 and C.S. Fadley 1,2 Department of Physics, UC Davis, Davis, CA, 95616, USA Materials Sciences Division, LBNL, Berkeley, CA, 94720, USA Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA. Department of Chemistry,The University of Tokyo, Tokyo,113-0033, Japan RIKEN, HYOGO 679-5148, Japan Beijing Synchrotron Radiation Laboratory, Beijing, China. Advanced Light Source, LBNL, Berkeley CA, 94720, USA National Institute for Advanced Industrial Science and Technolog (AIST), Tsukuba Central 4, Tsukuba 305-8562, Japan Present address: Physics Department, Stanford University, Stanford, CA, USA b Present address: Advanced Light Source, LBNL, Berkeley CA, 94720, USA c Present address: Heidelberg University, Heidelberg, Germany d Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973-5000, USA e Present address: IBM Almaden Research Center, San Jose, CA 95120, USA a ABSTRACT We have studied the temperature-dependent evolution of the electronic and local atomic structure in the cubic colossal magnetoresistive manganite La 1-x Sr x MnO 3 (x= 0.3 – 0.4) with core and valence level photoemission (PE), x-ray absorption specroscopy (XAS), x-ray emission spectroscopy (XES), resonant inelastic x-ray scattering (RIXS), extended x-ray absorption fine structure (EXAFS) spectroscopy and magnetometry. As the temperature is varied across the Curie temperature T C, our PE experiments reveal a dramatic change of the electronic structure involving an increase in the Mn spin moment from ≈ 3 μ B to ≈ 4 μ B , and a modification of the local chemical environment of the other constituent atoms indicative of electron localization on the Mn atom. These effects are reversible and exhibit a slow-timescale ≈ 200 K- wide hysteresis centered at T C . Based upon the probing depths accessed in our PE measurements, these effects seem to survive for at least 35-50 A inward from the surface, while other consistent signatures for this modification of the electronic structure are revealed by more bulk sensitive spectroscopies like XAS and XES/RIXS. We interpret these effects as spectroscopic fingerprints for polaron formation, consistent with the presence of local Jahn-Teller distortions of the MnO 6 octahedra around the Mn atom, as revealed by the EXAFS data. Magnetic susceptibility measurements in addition show typical signatures of ferro- magnetic clusters formation well above the Curie temperature.